[FIXED] 'org.h2.server.web.WebServlet' is not assignable to 'javax.servlet.Servlet,jakarta.servlet.Servlet'

Issue

I'm using jakarta.jakartaee-api 9.1.0 and H2 2.1.212.

I get this error when I try to add H2 Console Servlet to web.xml file:

'org.h2.server.web.WebServlet' is not assignable to 'javax.servlet.Servlet,jakarta.servlet.Servlet'

Here is my web.xml file:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="5.0"
         xmlns="https://jakarta.ee/xml/ns/jakartaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd">
    <data-source>
        <name>java:global/dataSource</name>
        <class-name>org.h2.jdbcx.JdbcDataSource</class-name>
        <url>jdbc:h2:mem:test;MODE=LEGACY</url>
    </data-source>

    <servlet>
        <servlet-name>H2Console</servlet-name>
        <servlet-class>org.h2.server.web.WebServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>H2Console</servlet-name>
        <url-pattern>/h2/*</url-pattern>
    </servlet-mapping>

    <servlet>
        <servlet-name>jakarta.ws.rs.core.Application</servlet-name>
    </servlet>
    <servlet-mapping>
        <servlet-name>jakarta.ws.rs.core.Application</servlet-name>
        <url-pattern>/api/*</url-pattern>
    </servlet-mapping>
</web-app>

How can I fix the error?

Solution

jakarta.* packages

The package namespace for Jakarta 9 and 9.1 is jakarta.*. This changed from the old javax.* naming during the transition of Oracle handing over Java EE to the Eclipse Foundation where it became Jakarta EE.

I poked around GitHub to find JakartaWebServlet. This seems to be the same Servlet but using the jakarta.* packages. You may be able to switch from:

<servlet-class>org.h2.server.web.WebServlet</servlet-class>

… to:

<servlet-class>org.h2.server.web.JakartaWebServlet</servlet-class>

Answered By - Basil Bourque
Answer Checked By - Mary Flores (JavaFixing Volunteer)